Psychosomatic Medicine 33:353-362 (1971)
© 1971 American Psychosomatic Society

Development and Mechanisms of Cardiorespiratory Responses to Maternal Deprivation in Rat Pups

¹ Department of Psychiatry, Montefiore Hospital and Albert Einstein College of Medicine 111 East 210 St, Bronx, NY.

Myron A. Hofer, MD, Department of Psychiatry, Montefiore Hospital, 111 East 210 St, Bronx, NY 10467

Cardiac and respiratory rates and an index of activity were recorded in rat pups separated from their mothers for 24 hours at 4, 14 and 21 days after birth. The cardiac and respiratory rates of pups separated at 14 days fell by 40%, while he percentage of time they were active was unchanged. In younger pups, the major response was respiratory, while 3-week-old pups showed only marginal trends in these measures. Experiments on 2-week-old pups with autonomic blocking agents and tactile stimulation revealed that the hearts of separated pups were capable of beating at normal rates but failed to do so, probably because of reduced sympathetic tone augmented by some degree of vagal restraint. Separation of 2-week-old pups in a novel environment led to more rapid responses than if pups remained in their home cage nest after removal of the mother. Nonlactating foster mothers failed to prevent the physiologic changes. The importance of the feeding experience to the maintenance of sympathetic tone in young rats is suggested and discussed.

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